At least some known X-ray and/or computed tomography (CT) detection systems include a secondary collimator to facilitate ensuring acceptable detector performance by excluding scatter X-rays from reaching the detector. In some known CT detection systems, the secondary collimator is coupled to a gantry such that the secondary collimator rotates with an X-ray source and the detector.
At least one known secondary collimator includes an array of identical modules (i.e., of 32×32 cells each) that are tiled side-by-side along an arc of the array. However, such tiling only allows for attachment on untiled ends of the array. When such an array is subjected to centrifugal loads, each module is deflected by an unacceptable amount. More specifically, because the gantry rotates about a point closer to the array than to a focal spot, the collimator modules are subjected to forces in a non-perpendicular or non-normal direction, which tends to bend the collimator, particularly at the ends of the array. Such bending and/or deflection of the collimator may allow radiation that should have been excluded from reaching the detector to be received by the detector and used in further processing. More specifically, any bending of the collimator de-focuses the collimator and frustrates the function of the collimator to allow only those X-rays that travel on a straight line between the X-ray source and the detector cell to be received at the detector cell. For example, each cell of the collimator is focused to a focal spot, and deflection of the collimator in any direction moves the cells out of such a focused condition. As such, the CT system may provide false positives or otherwise improperly detect materials and/or objects within a container being imaged.